Method and apparatus for allocating uplink resources

ABSTRACT

A method and an apparatus for allocating uplink resources includes transmitting an uplink grant (UL Grant) for an unlicensed component carrier (UCC) to a plurality of terminals, wherein the UL Grant for a first terminal among the plurality of terminals includes a resource allocation information in which a transmission timing of the uplink data of a second terminal among the plurality of terminals is considered.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication Nos. 10-2015-0051183, 10-2015-0067523, 10-2015-0135929 and10-2016-0043618 filed in the Korean Intellectual Property Office on Apr.10, 2015, May 14, 2015, Sep. 24, 2015, and Apr. 8, 2016, the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to an apparatus and a method forallocating uplink resources for transmission of uplink data.

(b) Description of the Related Art

In accordance with an increase in Internet users using a mobilecommunication system, mobile communications carriers are seeking anefficient method for increasing capacity of the mobile communicationsystem. The most efficient and intuitive method for increasing capacityof the mobile communication system is to increase a bandwidth byadditionally securing a frequency of a licensed band for the mobilecommunication system. The mobile communication carrier may efficientlyprovide a mobile communication service by exclusively using the securedlicensed band frequency, but there is a disadvantage that it costs a lotto license and use the frequency of the licensed band, and the frequencyof the licensed band allocated for the mobile communication system islimited. Accordingly, a method for providing the mobile communicationsystem using a frequency of an unlicensed band, a frequency of a TVwhite space (TVWS), or a frequency of a licensed/unlicensed band(hereinafter, referred to as ‘an unlicensed band’) shared by the mobilecommunication carriers in which a lot of relatively available frequencybands exist and costs are also inexpensive has been considered

A communication system using the frequency of the unlicensed band hasthe following limits.

First, in order to minimize an influence on another system sharing theunlicensed band, transmission power is limited. Therefore, in the casein which a licensed band system and an unlicensed band system aredeployed on the same place, a coverage hole may occur in the unlicensedband system, unlike the licensed band system.

In addition, for a fair coexisting with a neighboring unlicensed bandsystem, the frequency of the unlicensed band should be discontinuouslyor randomly used. As a result, transmission reliability of a controlchannel, a common channel, and the like used in the mobile communicationsystem may be decreased. Further, a regulation on the frequency of theunlicensed band should be obeyed.

For example, in order to transmit data, a system using the unlicensedband may perform a clear channel assessment (CCA) to search a channel infrequency resources and determine whether or not the channel is useddepending on the result of CCA, and even though a specific deviceoccupies the channel depending on the result of CCA, a channel occupancytime may be limited according to a frequency regulation. Further, thespecific device may not occupy the channel during a time exceeding amaximum channel occupancy time, and needs to additionally perform theCCA in order to re-occupy the channel.

Due to the limit of the unlicensed band system described above, ratherthan a standalone system that uses only the unlicensed band, a scenarioin which the unlicensed band supplements mutually with the licensed bandsystem has been examined. In this scenario, control functions thatrequire reliability such as a terminal control, a mobility management,and the like are performed in the licensed band, and traffic functionssuch as an increase in wireless transmission speed, a wireless trafficload distribution, and the like may be supplemented by the unlicensedband system.

That is, the system or carrier operated in the licensed band performsthe control and traffic functions, and the system or carrier operated inthe unlicensed band frequency performs the traffic function. Theabove-mentioned operation may be implemented by a carrier aggregation(CA) technology. For example, examples of a CA configuration of 3GPP LTEinclude a CA between an FDD carrier of the unlicensed band and a carrierof the licensed band (i.e., LTE), a TDD carrier of the unlicensed bandin which both uplink/downlink are operated and a carrier of the licensedband, and the like.

The cellular system using the unlicensed band has an advantage that itmay provide the mobile communication service of which service quality isguaranteed by utilizing inexpensive and rich frequency resources and anadvanced interference control technology. However, in order to securethe above-mentioned advantages while conforming to a variety ofregulations of the unlicensed band and coexisting with other unlicensedband systems, new coexistence technology and interference controltechnology are required. Particularly, due to characteristics of theunlicensed band, the device operated in the unlicensed bandoccupies/uses the channel, and in this case, in the case in which thecarrier aggregation technology is applied, the carrier aggregationtechnology that considers characteristics of the licensed band and theunlicensed band, and an operation method thereof are required. Inaddition, by reflecting limits (characteristics) for operating thedevice of the unlicensed band, a reliable wireless transmission serviceequivalent to an existing cellular system should be provided.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

An exemplary embodiment has been made in an effort to provide a methodfor allocating uplink resources of an unlicensed band by consideringdata transmission of a plurality of terminals. Another exemplaryembodiment has been made in an effort to provide an apparatus forallocating uplink resources of an unlicensed band by considering datatransmission of a plurality of terminals.

An exemplary embodiment provides a method for allocating resources foruplink data, the method including: transmitting an uplink grant (ULGrant) for an unlicensed component carrier (UCC) to a plurality ofterminals, wherein the UL Grant for a first terminal among the pluralityof terminals includes a resource allocation information in which atransmission timing of the uplink data of a second terminal among theplurality of terminals is considered.

The UL Grant for the first terminal may include the resource allocationinformation allowing the first terminal to perform a clear channelassessment (CCA) after the second terminal transmits the uplink data.

The UL Grant for the first terminal may include the resource allocationinformation allowing the first terminal to transmit the uplink dataafter the second terminal transmits the uplink data.

The transmitting of the UL Grant may include: transmitting the UL Grantto the plurality of terminals through a licensed component carrier(LCC).

Before the transmitting of the UL Grant, performing a clear channelassessment (CCA) in an unlicensed band, the transmitting of the UL Grantmay include: transmitting the UL Grant to the plurality of terminalsthrough the UCC, when a channel of the unlicensed band is occupied bythe CCA.

The UL Grant may include the resource allocation information allowingthe uplink data to be transmitted through the channel of the unlicensedband occupied by the CCA.

The method may further include transmitting a special signal forpreventing other devices from occupying the channel when the channel ofthe unlicensed band is occupied by the CCA.

The UL Grant may include a physical uplink shared channel (PUSCH) formatin which a transmission starting point and a transmission ending pointof the UL Grant are defined in a subframe unit, a slot unit, or a symbolunit.

Another exemplary embodiment provides method for transmitting uplinkdata, the method including: receiving an uplink grant (UL Grant) for anunlicensed component carrier (UCC) from a base station; performing aclear channel assessment (CCA) in a previous subframe before a subframefor the uplink data transmission which is indicated by the UL grant; andtransmitting the uplink data through the UCC when the channel of the UCCis occupied by the CCA.

The transmitting of the uplink data may include transmitting a specialsignal for preventing other devices from occupying the channel.

The transmitting of the uplink data may include transmitting the uplinkdata without the CCA in a next subframe of the subframe in which theuplink data is transmitted when a resource for the uplink data issuccessively allocated according to the UL grant.

The performing of the CCA may include randomly selecting a slot for theCCA from among a plurality of slots in the previous subframe; andperforming the CCA in the selected slot.

The transmitting of the uplink data may include transmitting the uplinkdata through a portion of symbol or slot included in the subframe forthe uplink data.

The method may further include transmitting no uplink data when thespecial signal is received from the base station or another terminal.

Another exemplary embodiment provides a base station including: at leastone processor; a memory, and a radio frequency (RF) unit, wherein atleast one processor executes at least one program stored in the memoryto perform

an operation of transmitting an uplink grant (UL Grant) for anunlicensed component carrier (UCC) to a plurality of terminals, and theUL Grant for a first terminal among the plurality of terminals includesa resource allocation information in which a transmission timing of theuplink data of a second terminal among the plurality of terminals isconsidered.

The UL Grant for the first terminal may include the resource allocationinformation allowing the first terminal to perform a clear channelassessment (CCA) after the second terminal transmits the uplink data.

The UL Grant for the first terminal may include the resource allocationinformation allowing the first terminal to transmit the uplink dataafter the second terminal transmits the uplink data.

When at least one processor performs the operation of transmitting theUL Grant, at least one processor may perform an operation oftransmitting the UL Grant to the plurality of terminals through alicensed component carrier (LCC).

Before at least one processor performs the operation of transmitting theUL Grant, at least one processor may further perform an operation ofperforming a clear channel assessment (CCA) in an unlicensed band, andwhen at least one processor performs the operation of transmitting theUL Grant, at least one processor performs an operation of transmittingthe UL Grant to the plurality of terminals through the UCC, when achannel of the unlicensed band is occupied by the CCA.

At least one processor may execute at least one program stored in thememory to further perform an operation of transmitting a special signalfor preventing other devices from occupying the channel when the channelof the unlicensed band is occupied by the CCA.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic views illustrating a method for allocatinguplink resources of an unlicensed band in a licensed band at the time ofa cross-carrier scheduling.

FIGS. 2A and 2B are schematic views illustrating a method for allocatinguplink resources of an unlicensed band at the time of a self scheduling.

FIGS. 3A to 3C are layout views illustrating a mobile communicationsystem in which an UCC is set and operated.

FIGS. 4A and 4B are schematic views illustrating a method for allocatinguplink resources so that uplink schedulings of a plurality of terminalsdo not overlap with each other according to an exemplary embodiment.

FIGS. 5A and 5B are schematic views illustrating a method for allocatinguplink resources so that uplink schedulings of a plurality of terminalsdo not overlap with each other according to another exemplaryembodiment.

FIGS. 6A and 6B are schematic views illustrating a method for allocatinguplink resources so that uplink schedulings of a plurality of terminalsdo not overlap with each other according to still another exemplaryembodiment.

FIGS. 7A and 7B are schematic views illustrating a method for allocatinguplink resources so that a plurality of terminals simultaneouslytransmit data according to an exemplary embodiment.

FIGS. 8A and 8B are schematic views illustrating a method for allocatinguplink resources so that a plurality of terminals simultaneouslytransmit data according to another exemplary embodiment.

FIGS. 9A and 9B are schematic views illustrating a method for allocatinguplink resources to a terminal through a clear channel according to anexemplary embodiment.

FIGS. 10A and 10B are schematic views illustrating a method forallocating uplink resources to a terminal through a clear channelaccording to another exemplary embodiment.

FIGS. 11A and 11B are schematic views illustrating a method fortransmitting data by a terminal after a resource reservation/occupationfailure of a base station according to an exemplary embodiment.

FIGS. 12A and 12B are schematic views illustrating a method forallocating uplink resources so that a CCA timing of a base station and adata transmission of a terminal do not overlap with each other accordingto an exemplary embodiment.

FIGS. 13A and 13B are views illustrating a method for repetitivelyscheduling uplink resources to a plurality of terminals by a basestation according to an exemplary embodiment.

FIGS. 14A and 14B are views illustrating a method for repetitivelyscheduling uplink resources to a plurality of terminals by a basestation according to another exemplary embodiment.

FIGS. 15A and 15B are views illustrating a cross-carrier scheduling fora multiplexing of an uplink according to an exemplary embodiment.

FIGS. 16A and 16B are views illustrating a self scheduling for amultiplexing of an uplink according to an exemplary embodiment.

FIGS. 17A and 17B are views illustrating a method for transmitting dataafter an uplink (UL) grant through a self scheduling according to anexemplary embodiment.

FIG. 18 is a view illustrating a PUSCH format according to the UL grantaccording to an exemplary embodiment.

FIG. 19 is a view illustrating a PUSCH format according to the UL grantaccording to another exemplary embodiment.

FIG. 20 is a view illustrating a cross-carrier scheduling in which theCCA is a frame based equipment (FBE) scheme according to an exemplaryembodiment.

FIG. 21 is a view illustrating a cross-carrier scheduling in which theCCA is a load based equipment (LBE) scheme according to an exemplaryembodiment.

FIG. 22 is a view illustrating a self scheduling in which the CCA is theFBE scheme according to an exemplary embodiment.

FIG. 23 is a view illustrating a self scheduling in which the CCA is theLBE scheme according to an exemplary embodiment.

FIG. 24 is a view illustrating a method in which a channel is occupiedby the self scheduling that performs the CCA once in a case in which theCCA is the FBE scheme according to an exemplary embodiment.

FIG. 25 is a view illustrating a method in which a channel is occupiedby the self scheduling that performs the CCA once in a case in which theCCA is the LBE scheme according to an exemplary embodiment.

FIG. 26 is a view illustrating a possible uplink/downlink subframeconfiguration according to an exemplary embodiment.

FIG. 27 is a view illustrating a transmission timing of uplink data ofthe uplink/downlink subframe configuration according to FIG. 26.

FIG. 28 is a view illustrating a possible uplink/downlink subframeconfiguration according to another exemplary embodiment.

FIG. 29 is a view illustrating a transmission timing of uplink data ofthe uplink/downlink subframe configuration according to FIG. 28.

FIG. 30 is a view illustrating a possible uplink/downlink subframeconfiguration according to still another exemplary embodiment.

FIG. 31 is a view illustrating a transmission timing of uplink data ofthe uplink/downlink subframe configuration according to FIG. 30.

FIG. 32 is a view illustrating a possible uplink/downlink subframeconfiguration according to still another exemplary embodiment.

FIG. 33 is a view illustrating a transmission timing of uplink data ofthe uplink/downlink subframe configuration according to FIG. 32.

FIG. 34 is a view illustrating a possible uplink/downlink subframeconfiguration according to still another exemplary embodiment.

FIG. 35 is a view illustrating a transmission timing of uplink data ofthe uplink/downlink subframe configuration according to FIG. 34.

FIG. 36 is a view illustrating a method for performing a self schedulingbased on a frame configuration in which an uplink and a downlink areoccupied at the same ratio according to an exemplary embodiment.

FIG. 37 is a view illustrating a method for performing a self schedulingbased on a frame configuration in which an uplink and a downlink areoccupied at the same ratio according to another exemplary embodiment.

FIG. 38 is a view illustrating a method for allocating resources to aplurality of terminals according to an exemplary embodiment.

FIG. 39 is a view illustrating a method for allocating resources to aplurality of terminals by a cross-carrier scheduling in a case in whichthe CCA is the FBE scheme according to an exemplary embodiment.

FIG. 40 is a view illustrating a method for allocating resources to aplurality of terminals by a cross-carrier scheduling in a case in whichthe CCA is the LBE scheme according to an exemplary embodiment.

FIG. 41 is a view illustrating a method for allocating resources to aplurality of terminals by a self scheduling in a case in which the CCAis the FBE scheme according to an exemplary embodiment.

FIG. 42 is a view illustrating a method for allocating resources to aplurality of terminals by a self scheduling in a case in which the CCAis the LBE scheme according to an exemplary embodiment.

FIGS. 43 and 44 are views illustrating a method for transmitting data bya terminal in a case in which a base station simultaneously occupiesuplink/downlink channels according to an exemplary embodiment.

FIGS. 45 and 46 are views illustrating a method for transmitting data bya terminal in a case in which a base station simultaneously occupiesuplink/downlink channels according to another exemplary embodiment.

FIGS. 47 and 48 are views illustrating a partial subframe of a method 1according to an exemplary embodiment.

FIGS. 49 and 50 are views illustrating a partial subframe of a method 2according to an exemplary embodiment.

FIGS. 51 and 52 are views illustrating a partial subframe of a method 3according to an exemplary embodiment.

FIG. 53 is a view illustrating a partial subframe of a method 4according to an exemplary embodiment.

FIG. 54 is a view illustrating a partial subframe of a method 5according to an exemplary embodiment.

FIGS. 55 and 56 are views illustrating a partial subframe of a method 1according to another exemplary embodiment.

FIGS. 57 and 58 are views illustrating a partial subframe of a method 2according to another exemplary embodiment.

FIGS. 59 and 60 are views illustrating a partial subframe of a method 3according to another exemplary embodiment.

FIGS. 61 and 62 are views illustrating a partial subframe of a method 4according to another exemplary embodiment.

FIG. 63 is a block diagram illustrating a wireless communication systemaccording to an exemplary embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments will be described in detail withreference to the accompanying drawings so that those skilled in the artmay easily practice the present invention. However, the presentinvention may be implemented in various different ways and is notlimited to the exemplary embodiments provided in the presentdescription. In the accompanying drawings, portions unrelated to thedescription will be omitted in order to obviously describe the presentinvention, and similar reference numerals will be used to describesimilar portions throughout the present specification.

Throughout the specification, a terminal may refer to a mobile station(MS), a mobile terminal (MT), an advanced mobile station (AMS), a highreliability mobile station (HR-MS), a subscriber station (SS), aportable subscriber station (PSS), an access terminal (AT), a userequipment (UE), a machine type communication (MTC) device, and the like,and may include functions of all or some of the MT, MS, AMS, HR-MS, SS,PSS, AT, UE, and the like.

In addition, a base station (BS) may represent an advanced base station(ABS), a high reliability base station (HR-BS), a node B, an evolvednode B (eNodeB), an access point (AP), a radio access station (RAS), abase transceiver station (BTS), a mobile multi-hop relay (MMR)-BS, arelay station (RS) serving as the base station, a relay node (RN)serving as the base station, an advanced relay station (ARS) serving asthe base station, a high reliability relay station (HR-RS) serving asthe base station, a small base station [femto base station (BS), a homenode B (HNB), a home eNodeB (HeNB), a pico BS, a macro BS, a micro BS,or the like], or the like, and may include all or some of the functionsof the ABS, the nodeB, the eNodeB, the AP, the RAS, the BTS, the MMR-BS,the RS, the RN, the ARS, the HR-RS, the small base station, and thelike.

FIGS. 1A and 1B are schematic views illustrating a method for allocatinguplink resources of an unlicensed band in a licensed band at the time ofa cross-carrier scheduling, and FIGS. 2A and 2B are schematic viewsillustrating a method for allocating uplink resources of an unlicensedband at the time of a self scheduling.

FIGS. 1A and 2A are schematic views illustrating a method for allocatingresources of an unlicensed band of a frame based equipment (FBE), andFIGS. 1B and 2B are schematic views illustrating a method for allocatingresources of an unlicensed band of a load based equipment (LBE). The FBEand the LBE are channel access schemes defined by ETSI EN301.893, 3GPPTR36.889 specification, a basic operation thereof applies a methoddescribed in the specification, and it is assumed in an exemplaryembodiment that a channel occupancy time is 4 ms. A cross-carrierscheduling refers to a scheduling scheme in which a base stationtransmits an uplink (UL) grant for an unlicensed component carrier (UCC)to a terminal through a licensed component carrier (LCC). In addition, aself scheduling refers to a scheduling scheme in which the base stationtransmits the UL grant for the UCC to the terminal through the same UCC.

Referring to FIGS. 1A and 1B, the base station allocates (UL grants)resources to the terminal through the cross-carrier scheduling. Inaddition, a UE2 and a UE4 are scheduled to transmit the UL grant in aprimary cell (PCell) and transmit data to the base station at a timingafter four subframes (based on an FDD). Here, in the case in which thePCell is operated in a TDD, an uplink scheduling timing of the terminalmay be four to seven subframes depending on an uplink/downlink (UL/DL)configuration. However, if another terminal (UE1) has already beenoccupying a channel when UE2 and the UE4 perform the CCA fortransmitting data at a scheduled timing, since the UE2 determines thatthe channel is occupied (or used) as the result of CCA, the UE2 may nottransmit the data at the scheduled timing. In this case, anotherterminal may be another device operated in the unlicensed band such asthe base station or WiFi. Similarly, a similar problem may also occur inFIGS. 2A and 2B illustrating a case of the self-scheduling.

FIGS. 3A to 3C are layout views illustrating a mobile communicationsystem in which an UCC is configured and operated.

Referring to FIG. 3A, indoor and outdoor low power cells in which theLCC and the UCC are operated in one cell are illustrated. In each of thecases, the PCell may be a macro cell, and a secondary cell (SCell) mayalso be co-located with the PCell and may also be non-co-located withthe PCell.

Referring to FIG. 3B, the PCell in which the LCC is operated, and the(low power) SCell in which the LCC and the UCC are operated areillustrated. The respective SCells in which the LCC and the UCC areoperated may be disposed at an indoor and an outdoor. The PCell may be amacro cell or a small cell, and the SCell in which the LCC is operatedand the SCell in which the UCC is operated may be co-located with eachother or may be non-co-located with each other.

Referring to FIG. 3C, the PCell in which the LCC is operated and the(low power) SCell in which the UCC is operated are illustrated. TheSCell in which the UCC is operated may be disposed at an indoor and anoutdoor, and the PCell in which the LCC is operated may be the macrocell or the small cell.

Hereinafter, a method for scheduling uplink resources in a case in whichthe terminal performs the CCA before transmitting the data will be firstdescribed.

FIGS. 4A and 4B are schematic views illustrating a method for allocatinguplink resources so that uplink schedulings of a plurality of terminalsdo not overlap with each other according to an exemplary embodiment.

In FIGS. 4A and 4B, the uplink resources are allocated by thecross-carrier scheduling, and in order for the terminal to transmituplink data using the resources allocated by the base station, theterminal performs the CCA and may transmit the data in the case in whicha resource occupancy is possible (idle).

Referring to FIG. 4A (FBE), the UE2 is allocated with the uplinkresources so as not to perform the CCA for a data transmission at atiming at which the UE1 transmits the data. Therefore, performing CCAand occupying the channel by the UE1 when the UE2 performs the CCA maybe prevented. Referring to FIG. 4B (LBE), the UE4 may perform the CCA(or an extended CCA (Ext-CCA)) at a timing independent from a datatransmission timing of the UE3. In addition, since the uplink resourcesare successively allocated to the UE4 by the cross-carrier scheduling,the UE4 may successively transmit the data through one CCA without anadditional CCA.

FIGS. 5A and 5B are schematic views illustrating a method for allocatinguplink resources so that uplink schedulings of a plurality of terminalsdo not overlap with each other according to another exemplaryembodiment.

In FIGS. 5A and 5B, the uplink resources are allocated by the selfscheduling, and the base station performs the CCA to use the channel forallocating the resources to the terminal.

Referring to FIG. 5A (FBE), since the base station performs the CCA at afixed position (idle period), the uplink resources need to be allocatedto the terminal by considering a timing at which the terminal transmitsthe data. In FIG. 5A, the UE1 performs the CCA in a next subframe of asubframe in which an uplink data transmission (UL data Tx) of the UE2occurs. Meanwhile, referring to FIG. 5B (LBE), in the case in which theterminal needs to transmit the data, the base station may relativelydetermine a timing at which the CCA is performed. Therefore, the basestation may elastically adjust the channel occupancy time so that theterminal may again use the channel occupied before the terminal performsthe CCA. In addition, in the case in which the resources aresuccessively allocated to the terminal, the terminal may transmit thedata by using the resources through one CCA.

FIGS. 6A and 6B are schematic views illustrating a method for allocatinguplink resources so that uplink schedulings of a plurality of terminalsdo not overlap with each other according to still another exemplaryembodiment.

Also in FIGS. 6A and 6B, the base station allocates the uplink resourcesby the self scheduling, and performs the CCA to use the channel forallocating the resources to the terminal.

Referring to FIG. 6A (FBE), the base station allocates the resources tothe terminal by adjusting the channel occupancy time (COT), and theterminal performs the CCA before transmitting the data through theallocated resources. In this case, a first subframe among the COT of thebase station of FIGS. 5A and 5B may also be used to allocate the uplinkresources in which the UL grant is transmitted. A method for adjustingthe COT of the base station of FIG. 6A (for example, according themethod, the COT is ended until the uplink data transmission is startedthrough the allocated resource in the case of the UL grant beingtransmitted on the first subframe) may also be applied to FIG. 6B (LBE).

In addition, referring to FIG. 6B, since a timing of the CCA is notfixed as compared to the FBE, and during the Ext-CCA a CCA slot may beselected randomly for the CCA, an ending timing of the CCA may not bealigned to a transmission unit for the data transmission (e.g., in thecase of the LTE, a timing of the subframe). In order to solve theabove-mentioned problem, a special signal may be transmitted rightbefore the data is transmitted. The special signal is indicated by ‘RSV(reservation)’ in FIG. 6B. The special signal may be similar to a signaltransmitted at the time of accessing/occupying the channel for adownlink data transmission from the base station. For example, theterminal may use the special signal so that other devices (e.g., WiFi,other base station (eNB), other terminals) operated in the unlicensedband do not access/occupy the channel after the CCA, in order totransmit the data in the resources allocated by the base station for theuplink data transmission. The special signal illustrated in FIG. 6B mayalso be used for the LBE or the FBE of a case in which the resources areallocated by the cross-carrier scheduling.

FIGS. 7A and 7B are schematic views illustrating a method for allocatinguplink resources so that a plurality of terminals simultaneouslytransmit data according to an exemplary embodiment, and FIGS. 8A and 8Bare schematic views illustrating a method for allocating uplinkresources so that a plurality of terminals simultaneously transmit dataaccording to another exemplary embodiment.

In FIGS. 7A and 7B, the uplink resources are allocated by thecross-carrier scheduling, and in FIGS. 8A and 8B, the uplink resourcesare allocated by the self-scheduling.

First, referring to FIGS. 7A and 8A in which the FBE is applied, a CCAstarting point and a CCA time (or CCA period) of a plurality ofterminals that intend to simultaneously transmit the data may beconfigured to be the same as each other. Therefore, the plurality ofterminals performing the CCA at the same timing all obtain the same CCAresult (either busy or idle), and in the case in which the channel is anidle, the data transmission is performed at the same timing, therebymaking it possible to implement a multiplexing between the plurality ofterminals.

In addition, also in FIGS. 7B and 8B in which the LBE is applied, theCCA starting point and the CCA time (or CCA period) are configured to bethe same as each other to each of the plurality of terminals, anaccess/occupancy timing of the channel of each of the terminals may beadapted to be the same as each other.

As described above, since the starting point of the CCA in the case ofthe LBE is not fixed as compared to the FBE, and during the Ext-CCA theCCA slot may be selected randomly for the CCA, the ending timing of theCCA may not be aligned to the transmission unit of the data. In order tosolve this problem, the RSV in which the special signal is transmittedmay be used right before the data is transmitted. The special signal maybe similar to a signal transmitted at the time of accessing/occupyingthe channel for a downlink data transmission from the base station. Forexample, the terminal may use the special signal so that other devices(e.g., WiFi, other base station (eNB), other terminals) operated in theunlicensed band do not access/occupy the channel after the CCA, in orderto transmit the data in the resources allocated by the base station forthe uplink data transmission. The special signal of FIGS. 7B and 8B mayalso be used in the FBE, similar to the LBE (i.e., similar to or thesame as the LBE).

The plurality of terminals simultaneously perform the CCA and transmitthe data may also be applied to a method in which the base stationperforms a scheduling for the data transmission of the terminal to theterminal, the terminal performs the CCA before the data transmission toreserve or hold the uplink resources, and the terminal then transmitsthe data, which will be described below in detail with reference toFIGS. 13 to 16.

FIGS. 9A and 9B are schematic views illustrating a method for allocatinguplink resources to a terminal through a clear channel assessment (CCA)of the base station according to an exemplary embodiment, and FIGS. 10Aand 10B are schematic views illustrating a method for allocating uplinkresources to a terminal through a clear channel assessment (CCA) of thebase station according to another exemplary embodiment.

According to the methods illustrated in FIGS. 9A, 9B, 10A, and 10B,since the base station performs the CCA for the data transmission of theterminal instead of the terminal, an overhead which may be caused in thecase in which the plurality of terminals perform the CCA as in themethod as described above may be reduced.

However, in this case, the terminal may not accurately know whether ornot the channel is occupied, after the base station performs the CCA. Inorder to solve the above-mentioned problem, such as the RSV of theforegoing LBE, by transmitting a fact that the channel is occupied toanother device as the special signal at the transmission timing of thedata, it is possible to suppress the channel access/occupancy by anotherdevice. In addition, the special signal may also be applied in thesimilar/same way for a predetermined time after the CCA of the FBE.

Meanwhile, if it is determined that the channel is occupied as a resultof CCA performance, the base station may not reserve the resources, andthe base station may inform the terminal through the licensed band thatit fails to reserve the resources.

FIGS. 11A and 11B are schematic views illustrating a method fortransmitting data by a terminal after a resource reservation/occupationfailure of a base station according to an exemplary embodiment.

In the case in which since there is no indication for a resourcereservation failure of the base station or the indication is omitted,the terminal does not know the resource reservation failure, theterminal may transmit the data using the allocated resources independentfrom a result of the CCA. In addition, in the case in which it isdetermined that the channel may be used and may be occupied as theresult of the CCA performance of the base station, the terminal mayreceive the special signal transmitted from the base station anddetermine the fact that the channel may be occupied, therebytransmitting the data through the allocated resources. Alternatively,whether or not the resource reservation succeeds may also be informed ofthe terminal through the licensed band by the base station. Referring toFIGS. 11A and 11B, the base station succeeds in occupying the channel ina first CCA, and each of the terminals transmits the data without theCCA during a next COT. However, even though the base station fails tooccupy the channel in a next CCA, each of the terminals does not awareof the channel occupancy failure (that is, regardless of the channeloccupancy result) and may transmit the data in the allocated resources.

FIGS. 12A and 12B are schematic views illustrating a method forallocating uplink resources so that a CCA timing of a base station and adata transmission of a terminal do not overlap with each other accordingto an exemplary embodiment.

Referring to FIG. 10A, since the uplink transmission of the UE1 isscheduled at second and fourth CCA (additional CCA) starting points ofthe base station, the UE1 may not transmit the data at the correspondingstarting points. In addition, referring to FIG. 10B, since the uplinktransmission of the UE3 is scheduled at the fourth CCA starting point ofthe base station, the UE3 may not transmit the data at the correspondingstarting point.

In order to solve the above-mentioned problem, referring to FIGS. 12Aand 12B, in the case in which the COT of the base station is limited andthe uplink data transmission of the terminal is scheduled at a timing atwhich the additional CCA is required according to a frequencyregulation, the resources may be allocated so that the CCA of the basestation and the data transmission of the terminal do not overlap witheach other. That is, resource allocation information of scheduling theuplink data of each of the terminals at a timing after the additionalCCA of the base station may be included in the UL grant transmitted tothe terminal by the base station after the first CCA.

FIGS. 13A and 13B are views illustrating a method for scheduling uplinkresources at the same timing to a plurality of terminals by a basestation according to an exemplary embodiment, and FIGS. 14A and 14B areviews illustrating a method for scheduling uplink resources at the sametiming to a plurality of terminals by a base station according toanother exemplary embodiment.

In FIGS. 13A and 13B, the uplink resources are allocated to theplurality of terminals by the cross-carrier scheduling, and in FIGS. 14Aand 14B, the uplink resources are allocated to the plurality ofterminals by the self scheduling.

Referring to FIGS. 13A, 13B, 14A, and 14B, since the base stationreserves the resources for occupying/using the channel through the CCA,the base station allocates the resources to two or more terminals at thesame timing, thereby allowing the terminal to transmit the data.

In this case, when the base station occupies/uses the channel after theCCA, the base station transmits the special signal, thereby making itpossible to inform the terminal receiving the UL grant for the datatransmission about the channel occupancy. Thereafter, the terminal maytransmit the data through the resources allocated by the UL grant. Such“CCA+RSV (reservation)” may be performed in every uplink datatransmission unit (e.g., a subframe unit), and several data transmissionunits may be reserved. In this case, even in the case in which the datatransmission timing of the terminal is allocated, for example, in two orthree data transmission unit through the special signal transmittedafter the CCA, the terminal may transmit the data without the additionalCCA (omitting the CCA) of the base station. If the special signal is nottransmitted, the terminal receiving the UL grant determines that thechannel is occupied by another device, and does not transmit the data inthe resources allocated by the UL grant.

Meanwhile, a certain level or more of energy of the special signal maybe detected through an “energy detection” or may be detected through “asignal detection”. Such special signal may be applied in the same wayeven in the case in which the uplink resources are allocated by the selfscheduling of the base station. In addition, unlike the downlink data,the special signal for the uplink data may be newly defined, and in thiscase, the newly defined special signal may be applied for a downlinkdata reception and an uplink data transmission of the terminal.Alternatively, a section in which the downlink data and the uplink dataare transmitted is configured, and in the case in which the specialsignal is transmitted in the configured section, the terminal maydetermine whether or not the channel is used through the special signalto occupy/use the channel. In addition, the special signal may also bedefined in the form which is the same as or similar to a physicalcontrol channel indicating information used for a resource allocationsuch as PDCCH defined in LTE, or information defined in the physicalcontrol channel to indicate the resource allocation.

Hereinafter, a method for simultaneously transmitting the data in theunlicensed band by the plurality of terminals will be described.

In order for the base station to allocate the resources for the datatransmission to the plurality of terminals, the base station may eachallocate the resource to every one terminal, or may collectivelyallocate the resource to the plurality of terminals. In the case inwhich the base station collectively allocates the resource to theplurality of terminals at a time, parameters and the value of thoseparameters for performing the CCA may be applied to the plurality ofterminals in the same way. The method for allocating the resources isdescribed based on a 3GPP LTE system, but may also be applied to otherwireless access systems.

Operations of the base station and the terminal for performing the CCAand transmitting the data by the terminal are as follows.

According to an exemplary embodiment, in the case in which the basestation allocates (UL grant) the resources to the terminals using thePDCCH, the base station may additionally transmit value of parameters(set value) for performing the CCA. In this case, the setting value forperforming the CCA may also be included in the PDCCH, may also betransmitted in an upper layer such as an RRC layer (i.e., RRC levelsignaling), or may also be transmitted through an MAC control element(CE), or the like, and a setting value for performing the CCA predefinedbetween the base station and the terminal may also be used. According toan exemplary embodiment, the setting value for performing the CCA mayinclude a timing at which the CCA is performed, a CCA slot (e.g., may berandomly selected between 1 to q to perform the Ext-CCA in the case ofthe LBE, and may be a value for performing the CCA in the case of theFBE), a fixed frame period for operating the FBE in the case of theterminal set to the FBE, and the like. In this case, as the fixed frameperiod, the same value may be always applied, or the fixed frame periodmay be preset, or a predefined value may be used. If the setting valuefor performing the CCA is not received from the base station, theterminal may randomly select the setting value for performing the CCA,or may select the setting value for performing the CCA according to themethod defined by a regulation of the unlicensed band, or may intactlymaintain the setting value which is previously received from the basestation. In addition, in the case in which the CCA slot value in whichthe channel is determined to be “busy” at the time of a previous CCA anda countdown which is frozen exists, and the channel is again determinedto be “busy (or occupied)” as a result of a next CCA, the terminal mayreuse the CCA slot value frozen at the next CCA to again countdown theCCA slot value and may send the channel at the same time.

According to another exemplary embodiment, in order for the terminalreceiving the UL grant to transmit a physical uplink shared channel(PUSCH) (i.e., UL data), the terminal is instructed (special signaltransmission instruction) to transmit the special signal until atransmission timing of the PUSCH.

The special signal transmission instruction may also be included in thePDCCH, and may also be separately transmitted when time is availablebefore a PUSCH transmission after the CCA. Otherwise, the base stationdoes not transmit the special signal. In the case in which the basestation occupies the resources for the terminals and allows theterminals to use the resources, the base station performs the CCA andmay transmit the UL GRANT, or the like in the case in which the channelmay be occupied.

The special signal may also be instructed to be transmitted to all ofthe respective terminals at the time of the UL Grant, and may also beinstructed to be included in the PDCCH and transmitted to only aspecific terminal (e.g., a terminal performing the CCA) or someterminals.

Meanwhile, according to another exemplary embodiment, except theresources for the data transmission (PUSCH), the configured values suchas the CCA starting point, the CCA slot, and the like may be transmittedat the same value. In this case, the terminal is guided tosimultaneously transmit the data. The CCA starting point may be set toimmediately after the downlink data transmission of the base station (asubframe unit, a slot unit, a symbol unit, or the like), or may bedefined as a start timing of a specific subframe and a specific positionin the specific subframe (e.g., from a start position of a slot, aspecific symbol in the subframe). Similarly, a CCA ending point may beset to an ending timing of the specific subframe or slot, the specificsymbol, or the like. In order to prevent another device from accessingthe channel or occupying the channel during a time from the CCA startingpoint to the CCA ending point, the special signal may be configured ormay be instructed to the terminal to be transmitted from the CCAstarting point to the CCA ending point.

The terminal receiving the UL Grant from the base station performs theCCA at a later set timing using the resources allocated by the UL Grant.In this case, the CCA may comply with the set CCA value to transmit thedata. Hereinafter, ‘the set timing’ will be described base on after foursubframes after the PCell (based on the FDD) transmits the UL Grant.‘The configured timing’ may be varied depending on an UL/DLconfiguration (e.g., four to seven subframes) in the TDD, and a basictiming described in 3GPP TS36.211, 36.212, 36.213, or the like may beapplied. As a result of performing the CCA by the terminal, if it isdetermined that the channel is “busy or occupied”, the terminal does nottransmit the data, and may inform the base station about an occupancyfact of the channel through the licensed band.

However, as a result of performing the CCA by the terminal, if it isdetermined that the channel is available (idle), the terminal transmitsthe data. In the case in which the channel may be accessed/occupied, theterminal transmits the special signal when the special signal isrequired, and transmits the PUSCH through the allocated resources.

The terminal may perform the CCA before every data transmission, and maydetermine whether or not the data is transmitted through the specialsignal at a specific timing (e.g., a start timing of the UL period)instead of occupying the channel, or may transmit the data according tothe transmission unit. In this case, the base station may also transmitthe special signal, and the terminal performing the CCA may alsotransmit the special signal. The special signal may also be used forpurpose of determining that the channel is available as a result of theCCA, and may also be used to align the transmission unit (e.g., asubframe boundary) for the data transmission.

Meanwhile, operations of the base station and the terminal fortransmitting and receiving the special signal are as follows.

The special signal according to an exemplary embodiment may betransmitted by the base station or the terminal. In the case in whichthe base station attempts to reserve the resources through the CCA forthe data transmission, the special signal may be transmitted from thebase station. Alternatively, the special signal may be transmitted fromthe terminal performing the CCA for the data transmission.

A determination whether or not the channel is occupied by the specialsignal and an operation according to the determination may be performedas follows.

The subject (base station or terminal) performing the CCA transmits thespecial signal when it is determined that the channel may be occupiedthrough the CCA. In this case, in the case in which it is determinedthat the channel is already occupied by another device as a result ofthe CCA, since the channel may not be occupied/used, the base station orthe terminal does not transmit the special signal.

The terminal transmitting the special signal may transmit the data usingthe resources allocated from the base station.

The base station transmitting the special signal may prepare (expect) areception of the data from the terminal to which the resources areallocated through the UL Grant.

In the case in which the terminal receives the special signal from thebase station or another terminal, the terminal transmits the data usingthe resources allocated by the base station.

In this case, the special signal may be some or all of an uplinktransmission signal such as a physical downlink control channel (PDCCH),a physical random access channel (PRACH), a sounding reference signal(SRS), a physical uplink control channel (PUCCH), a physical uplinkcontrol shared channel (PUSCH), an uplink dedicated demodulationreference signal (DMRS), or the like which may be transmitted by theterminal of 3GPP LTE, or a form which may be repetitively transmittedacross the entire band, or a random value (e.g., “111 . . . 111”,“101010. . . ”, etc.).

The resources for transmitting the special signal may be all subcarriersof the entire band used for the uplink, or may also be transmitted onlyin the same subcarrier as the resource region allocated for transmittinguplink data. Alternatively, as the resource region for transmitting thespecial signal, the resource region which is allocated by the basestation or is preset may be used, or the resource region fortransmitting the special signal may be configured/instructed through asignal of an upper RRC level or through an MAC CE, or the like.

FIGS. 15A and 15B are views illustrating a cross-carrier scheduling fora multiplexing of an uplink according to an exemplary embodiment, andFIGS. 16A and 16B are views illustrating a self scheduling for amultiplexing of an uplink according to an exemplary embodiment.

As described above, in the case in which the plurality of terminalsperform the CCA at the same starting point, each of the terminalsperforms the CCA based on a setting value related to the same CCA at thesame starting point, and may transmit the special signal when thechannel may be occupied as a result of the CCA. In this case, theterminal (the UE2 or UE3 of FIGS. 15A, 15B, 16A, and 16B) receiving thespecial signal at a predetermined time (e.g., within the Max COT) mayomit the CCA for the data transmission and may transmit the data. Thedata at a timing at which the Max COT is expired is scheduled byconsidering the case in which the base station allocates the resources,such that the frequency regulation may be conformed. A data transmissionformat according to the frequency regulation will be described below indetail.

Meanwhile, the terminal which does not receive the special signal inFIGS. 13A to 16B may itself perform the CCA to transmit the data and maythen transmit the special signal. The same CCA related information (theCCA starting point, the CCA time (slot), etc.) may be provided orconfigured (or pre-configured) to the terminal attempting the datatransmission at the same timing so that services of two or moreterminals may be provided.

FIGS. 17A and 17B are views illustrating a method for transmitting dataafter an uplink (UL) grant through a self scheduling according to anexemplary embodiment.

As described above, the terminal transmits the data in the allocatedresources, at a specific timing after the UL Grant transmitted by thebase station. In this case, the specific timing is a timing after foursubframes after the PCell (based on the FDD) transmits the UL Grant, ora timing after four to seven subframes according to the UL/DLconfiguration in the TDD. However, due to the frequency regulation foroperating the unlicensed band, the terminal may not transmit the data inthe specific subframe. Therefore, according to an exemplary embodiment,a starting/ending timing of the PUSCH, which is the subframe unit, maybe determined as an arbitrary timing in the subframe (fractionaltransmission: shorter transmission unit compared to the subframe unit).In this case, the arbitrary timing in the subframe may be the start/endtiming of the slot or the specific symbol. In this case, the terminalmay transmit the data at a timing allocated to the UL Grant despite thefrequency regulation of the unlicensed band. For example, referring toFIG. 17A, the UE2 may not occupy all of the subframes allocated to theUL Grant, but may terminate the data transmission in the slot or thesymbol in the corresponding subframe, thereby making it possible totransmit the uplink data even in some of the subframes. Although FIGS.17A and 17B illustrate the case in which the resources of the unlicensedband are allocated by the self scheduling by way of example, theresource allocation of the unlicensed band may also be applied to thecase of the cross-carrier scheduling.

FIG. 18 is a view illustrating a PUSCH format according to the UL grantaccording to an exemplary embodiment and FIG. 19 is a view illustratinga PUSCH format according to the UL grant according to another exemplaryembodiment.

The terminal may transmit the PUSCH at a specific timing after the ULGrant according to the format illustrated in FIG. 18. Referring to FIG.18, the PUSCH format defines a transmission starting point and atransmission ending point of the uplink data as the slot unit, thesubframe unit, or the specific timing (i.e., the symbol unit) in thespecific frame. In this case, the RSV (reserved) is the special signaland may be omitted as needed. A subframe i−1 in the formats (e) to (h)of FIG. 18 may be used or may not be used as the downlink data. Thedownlink data is illustrated in the formats (a) to (d) of FIG. 18,however a subframe may also not be used as the downlink data.

The formats (a) to (h) of FIG. 18 are formats which may be applied inthe case in which the terminal performs the CCA and transmits the data.The formats (i) to (o) of FIG. 18 are formats which may be applied tothe case in which the base station reserves the resources, and even inthe case in which the base station reserves the resources, the terminalmay transmit the data by applying the formats (a) to (h). In the formats(a) to (d) of FIG. 18, the terminal may transmit the uplink data at asubframe i+k (for example, k=4) in the case in which the UL Grant is atthe subframe i. As in the formats (h), (l), (m), and (o), a HARQ timingof a HARQ ACK/NACK for the case in which the PUSCH is transmitted acrosstwo subframes may be defined according to a specific subframe (forexample, second (later portion) or first subframe) among the twosubframes.

Referring to FIG. 19, the terminal receiving the UL Grant at a subframem−4 may transmit the data after performing the CCA at a subframe m.Alternatively, in the case in which the UL Grant is transmitted to theterminal at the subframe m, the terminal may transmit the data using oneof the formats (a) to (o) at a subframe m+4 as a response for the ULGrant.

The formats (a) to (d) of FIGS. 18 and 19 may be applied similarly to aspecial subframe according to a TDD frame format defined by a 3GPP LTEstandard, and the terminal may perform the CCA in a guard period (GP) ormay perform the CCA in some or all of an uplink pilot time slot (UpPTS)or a period for transmission of SRS, or a first subframe after thespecial subframe.

Hereinafter, a method for adjusting a transmission timing of the uplinkdata after the UL Grant will be described.

For an operation according to the frequency regulation of the unlicensedband, the terminal may set an arbitrary timing in the subframe, not thesubframe unit, as the starting/ending timing of the PUSCH, at a timingallocated after the UL Grant. Alternatively, according to anotherexemplary embodiment, the base station may adjust a transmission timingof the uplink data and may provide a service to the terminal.

In order for the base station to adjust the transmission timing of theuplink data and provide the service to the terminal, the base stationmay expect the receiving timing of the uplink data after transmittingthe UL Grant at a subframe n and the terminal may determine thetransmission timing of the uplink date after receiving the UL Grant at asubframe n by considering only a time in which the channel is actuallyoccupied, and may follow the following Equation 1.n+max{k,T_(inter-tx)}  [Equation 1]

In Equation 1, k is the transmission/receiving timing (i.e., thesubframe) of the uplink data transmitted after receiving/transmittingthe UL Grant (subframe n) by terminal/base station defined in 3GPP. Inthe case in which the PCell is the FDD, k may be 4 (subframe), and inthe case in which the PCell is the TDD, k may be 4 to 7 (subframe)according to the UL/DL configuration. T_(inter-tx) is a time (subframeunit) up to an uplink subframe which may be occupied/used through theCCA after receiving the UL Grant.

FIG. 20 is a view illustrating a cross-carrier scheduling in which theCCA is a frame based equipment (FBE) scheme according to an exemplaryembodiment, FIG. 21 is a view illustrating a cross-carrier scheduling inwhich the CCA is a load based equipment (LBE) scheme according to anexemplary embodiment, FIG. 22 is a view illustrating a self schedulingin which the CCA is the FBE scheme according to an exemplary embodiment,and FIG. 23 is a view illustrating a self scheduling in which the CCA isthe LBE scheme according to an exemplary embodiment.

In FIGS. 20 to 23, it is assumed that k is 4, and in the case of theTDD, k may be applied as 4 to 7. In the case in which the uplink dataoccurs and it is necessary to transmit the uplink data, the terminal mayperform the CCA, and occupy the channel, thereby transmitting the data.

Referring to FIGS. 20 and 21, in the case of an uplink cross-carrierscheduling, the resources are allocated through the licensed band, andthe terminal generates a virtual frame from a timing (subframe n) atwhich the UL Grant is received, and performs the CCA before a k(=4)-thsubframe after the timing at which the UL Grant is received. Inaddition, in the case in which the terminal occupies the channel afterperforming the CCA, the terminal transmits the data at a timing n+k whena timing at which the data may be transmitted is less than or equal tok. However, in the case in which the terminal does not occupy thechannel as a result of the CCA and additionally performs the CCA to thenoccupy the channel, since T_(inter-tx) becomes longer than k, theterminal omits T_(inter-tx), and transmits the uplink data by regardingthe channel occupancy time after receiving the UL Grant as the uplinksubframe. In this case, since the uplink resources are allocated by thecross-carrier scheduling, in the case in which the terminal receives theUL Grant from the base station while transmitting the uplink data, theterminal may generate the virtual frame from the timing at which the ULGrant is received and may transmit the data.

Referring to FIGS. 22 and 23, in the case of the uplink self scheduling,the base station performs the CCA for allocating the resources throughthe UL Grant and the CCA for the uplink data transmission. The virtualframe is generated from the resource allocation timing (the receptiontiming of the UL Grant). In addition, if the channel is occupiedaccording to the CCA result until a timing at which the data may betransmitted (for example, a timing n+p when p is less than or equal tok), the terminal transmits the uplink data at a data transmission timing(timing n+k). However, in the case in which the channel is not occupiedas a result of the CCA and the channel is occupied as a result of theadditional CCA, since T_(inter-tx) becomes longer than k, the terminaldoes not consider T_(inter-tx) to determine the data transmission timing(n+k), and transmits the uplink data after regarding the channeloccupancy time after receiving the UL Grant as the subframe.

Referring to FIGS. 22 and 23, in the uplink data transmission throughthe uplink cross-carrier scheduling and the self scheduling, the basestation performs the CCA to transmit the UL Grant. In this case, thebase station may include related information in the “RSV” transmittedafter the CCA so that the channel occupancy/use for transmitting the ULgrant and the channel occupancy/use for the uplink data transmission maybe classified. In this case, the “RSV” may be used for purpose of a timealignment or a subframe boundary alignment for the data transmissionafter an additional CCA and for purpose of preventing the channeloccupancy/use of other devices (e.g., WiFi device, other eNBs, UE, etc.)between the CCA and the data transmission timing. In this case, the“RSV” may include some or all of information for a time/channelsynchronization for the data transmission, a distinction of a datatransmission device, and the like.

Referring to FIGS. 20 and 22, in the case in which the CCA of the FBEscheme is performed, the CCA for the data transmission is performed inan idle period which is uniformly given. Referring to FIGS. 21 and 23,in the case in which the CCA of the LBE scheme is performed, the CCA forthe data transmission is performed before a timing k (immediately beforethe timing k) for the data transmission after receiving the UL Grant.

While the additional CCA is performed, in the case in which the terminalreceives a new UL Grant from the base station, or a predetermined timelapses, or the terminal does not transmit the uplink data at the timingn+k as a result of the CCA, the terminal does not transmit the datatransmission, and may transmit the uplink data by the newly received ULGrant. In addition, in the case in which the base station occupies theresources for the downlink data transmission at a timing n+k through theCCA, the terminal may not transmit the uplink data at the timing n+kregardless of the reception of the UL Grant transmitted from the basestation at a timing n.

FIG. 24 is a view illustrating a method in which a channel is occupiedby the self scheduling that performs the CCA once in a case in which theCCA is the FBE scheme according to an exemplary embodiment, and FIG. 25is a view illustrating a method in which a channel is occupied by theself scheduling that performs the CCA once in a case in which the CCA isthe LBE scheme according to an exemplary embodiment.

Referring to FIG. 24, in the case in which the CCA of the FBE scheme isperformed, if the channel is not occupied by the terminal or the basestation, the base station or the terminal waits up to a next idle periodand then again performs the CCA. Meanwhile, referring to FIG. 25, in thecase in which the CCA of the LBE scheme is performed, if the basestation or the terminal does not occupy the channel through the CCA, thebase station or the terminal may occupy the channel by immediatelyperforming the additional CCA. In common in the FBE scheme and the LBEscheme, the base station and the terminal generate the virtual subframefrom the transmission/reception timing of the UL Grant, and transmit theuplink data in a k-th subframe after the subframe receiving the UL Grantwithin the virtual subframe. That is, since the downlink/uplink data maybe transmitted through the CCA (the CCA for the resource allocation)once, the terminal may not additionally perform the CCA for the datatransmission.

As described above, since the CCA is performed to transmit the uplinkdata due to the limit of the COT and the uplink data is transmitted, thetransmission timing (k) of the data after receiving the UL Grant may notbe corrected.

FIG. 26 is a view illustrating a possible uplink/downlink subframeconfiguration according to an exemplary embodiment and FIG. 27 is a viewillustrating a transmission timing of uplink data of the uplink/downlinksubframe configuration according to FIG. 26.

Referring to FIG. 26, the possible uplink/downlink subframeconfiguration of the virtual frame generated from the UL Granttransmitting/receiving timing is illustrated, and the case in which theCOT after the CCA is 4 ms is illustrated. FIG. 27 illustrates thetransmission timing of the uplink data according to the subframeconfiguration illustrated in FIG. 26, wherein a timing at which theuplink data is transmitted based on a current subframe is indicated in aunit of 1 ms. The transmission timing of the uplink data illustrated inFIG. 27 may follow Equation 1. In this case, one subframe configurationof the subframe configurations illustrated in FIG. 26 may be applied toevery CCA.

FIG. 28 is a view illustrating a possible uplink/downlink subframeconfiguration according to another exemplary embodiment and FIG. 29 is aview illustrating a transmission timing of uplink data of theuplink/downlink subframe configuration according to FIG. 28.

Referring to FIG. 28, in order to transmit the uplink data at apredetermined timing (for example, k=4) after the subframe receiving theUL Grant, the subframe configuration after a second CCA may bedetermined depending on a first frame structure. For example, in thecase in which an UL subframe of a first frame is across the last twosubframes (No. 1), first two subframes of a second subframe may beconfigured of UL, and the remaining two subframes may be configured ofDL. In this case, the transmission timing of the uplink data may beguaranteed.

FIG. 30 is a view illustrating a possible uplink/downlink subframeconfiguration according to still another exemplary embodiment and FIG.31 is a view illustrating a transmission timing of uplink data of theuplink/downlink subframe configuration according to FIG. 30.

Referring to FIG. 30, in the case in which the COT is 10 ms, theuplink/downlink subframe configuration according to another exemplaryembodiment is similar to a TDD frame configuration defined by 3GPP. Thatis, a new frame configuration according to FIG. 30 may be added to amethod in which the virtual subframe is generated by virtuallyconnecting the frames configured for each of CCAs, and the UL subframeis initially transmitted at a timing of 4 ms after receiving the ULGrant within the generated virtual subframe. Therefore, the transmissiontiming of the uplink data is defined as illustrated in FIG. 31. In thiscase, in the case of the subframe in which both the uplink/downlink areincluded, the uplink data is not transmitted, and it may be defined thatthe uplink data is transmitted at a next UL subframe. That is, exceptthe case in which all of the subframes are UL or DL (frame configurationNo. 10), similarly to the TDD frame configuration, the same frameconfiguration may be regulated to every CCA.

FIG. 32 is a view illustrating a possible uplink/downlink subframeconfiguration according to still another exemplary embodiment, FIG. 33is a view illustrating a transmission timing of uplink data of theuplink/downlink subframe configuration according to FIG. 32, FIG. 34 isa view illustrating a possible uplink/downlink subframe configurationaccording to still another exemplary embodiment, and FIG. 35 is a viewillustrating a transmission timing of uplink data of the uplink/downlinksubframe configuration according to FIG. 34.

Referring to FIGS. 32 and 34, each of the frame configurationsrepetitively occupies the DL/UL by 4 ms, FIG. 32 illustrates a case inwhich the channel occupancy time is 4 ms, and FIG. 34 illustrates a casein which the channel occupancy time is 10 ms. In addition, referring toFIGS. 33 and 35, according to each of the frame configurations, thetransmission timing of the uplink data after the subframe receiving theUL Grant is fixed to k(=4) in the virtually generated frame.

FIG. 36 is a view illustrating a method for performing a self schedulingbased on a frame configuration in which an uplink and a downlink areoccupied at the same ratio according to an exemplary embodiment and FIG.37 is a view illustrating a method for performing a self schedulingbased on a frame configuration in which an uplink and a downlink areoccupied at the same ratio according to another exemplary embodiment.

In FIG. 36, the CCA may be performed according to the FBE scheme, and inFIG. 37, the CCA may be performed according to the LBE scheme. Inaddition, in common in FIGS. 36 and 37, the frame configuration occupiesDL and UL of the case in which the channel occupancy time is 4 ms at thesame ratio (1:1), and the uplink/downlink subframes are eachrepetitively occupied by 4 ms. Referring to FIGS. 36 and 37, as in thecase in which a specific frame after the CCA starts with the DLsubframe, and a frame after a next CCA starts with the UL subframe,information for distinguishing consecutive frames configuring thevirtual frame may be included in a reservation signal transmitted afterthe CCA. For example, the reservation signal may include information ona first portion or a second portion of the virtual frame such as whetheror not the frame “starts from the DL subframe” or “starts from the ULsubframe”. The reservation signal including the information fordistinguishing the consecutive frames configuring the virtual frame mayalso be applied to a case in which the channel occupancy time is not 4ms (e.g., 10 ms). In addition, a configuration of the second frame maybe determined according to a configuration of the last four subframes ofthe first frame. For example, in the case in which the last subframe ofthe first frame is “DL, DL, DL (or DL+UL), and UL”, a start of thesecond frame may be configured in a form of “UL, UL, UL, and DL”. Inaddition, the DL and UL subframes are each repetitively occupied at thespecific ratio (M:N in which M≠N, for example, the number M of the DLsubframes and the number N of the UL subframes) as the frameconfiguration.

The method for adjusting the transmission timing of the data afterreceiving the UL Grant described above may be included in thereservation signal (or an initial signal, a preamble, or the like)transmitted before the data is transmitted after performing the CCA, ormay be included in the PDCCH. Alternatively, the above-mentioned methodmay be transmitted in the upper layer (RRC level signaling), or may alsobe transmitted using MAC CE or the like, and a predefined value may alsobe used. In addition, in this case, an index (i.e., configuration #)generated by indexing of the frame configuration is configured for theterminal in advance, thereby making it possible to transmit and receivethe data between the base station and the terminal by an accuratespecification.

Hereinafter, a method for adjusting a transmission timing of the uplinkdata after receiving the UL Grant (at subframe n) to provide a serviceto a plurality of terminals will be described.

FIG. 38 is a view illustrating a method for allocating resources to aplurality of terminals according to an exemplary embodiment.

For example, as a result obtained by performing the CCA by the UE1 totransmit the uplink data in the subframe n+k, if the channel is “busy”and as a result obtained by additionally performing the CCA by the UE1to transmit the uplink data in a subframe n+k+m (m≥1), if the channel is“idle”, the UE1 transmits the uplink data in the subframe n+k+m.However, in this case, if the UE2 also performs the CCA to transmit thedata in the subframe n+k+m, the UE1 and the UE2 may simultaneouslydetermine that the channel is “idle”. As a result, since the uplink datais transmitted to the base station from the UE1 and UE2 in the sameresource, the base station may not properly receive the uplink data. Inorder to solve the above-mentioned problem, 1) when the uplink data istransmitted to the base station from the plurality of terminals in thesame resource, the base station transmits the new UL Grant to theplurality of terminals to induce retransmission of the uplink data, or2) it is prevented to allocate the same resource to the plurality ofterminals by the base station, thereby making it possible to prevent theuplink data from being transmitted at the same timing. Alternatively, 3)the base station does not allocate the same resource on a frequency axisto the plurality of terminals during the COT, thereby allowing the basestation to receive the uplink data transmitted from the plurality ofterminals, or 4) as a result obtained by performing the CCA fortransmitting the uplink data in the subframe n+k, if the channel is“busy”, it may be set that the terminal does not transmit the uplinkdata in the subframe n+k. Here, in the case in which the channeloccupancy in the CCA for transmitting the uplink data in the subframe nfails and the uplink data is not transmitted, an instruction oftransmitting the uplink data in a subsequent subframe (e.g., thesubframe n+k+m) through the additional CCA or allowing the additionalCCA not to be performed may be included in the UL Grant, or transmittedthrough the upper layer (RRC level signaling), or may be transmittedusing the MAC CE, or the like, and a preset value may also be used.

FIG. 39 is a view illustrating a method for allocating resources to aplurality of terminals by a cross-carrier scheduling in a case in whichthe CCA is the FBE scheme according to an exemplary embodiment and FIG.40 is a view illustrating a method for allocating resources to aplurality of terminals by a cross-carrier scheduling in a case in whichthe CCA is the LBE scheme according to an exemplary embodiment.

According to an exemplary embodiment, in order to provide the service tothe plurality of terminals, the method for transmitting the specialsignal and the method for adjusting the transmission timing of theuplink data described above may be combined.

Referring to FIGS. 39 and 40, first, if the base station allocates (ULGrant) the uplink resources through the licensed band, the terminals(UE1 and UE3) receiving the UL Grant perform the CCA to transmit theuplink data in the corresponding unlicensed band and occupy the channel.In the case in which the UE1 and UE3 occupy the channel through the CCA,the UE1 and UE3 transmit “RSV”, and the base station receiving theuplink data (UL data Tx 1 and UL data Tx 2′) “RSV” in the resourceallocated through the UL Grant expects the uplink data from the terminalreceiving the UL Grant and prepares to receive the uplink data. In thiscase, even in the case in which the base station does not receive “RSV”,the base station may expect the uplink data and may prepare to receivethe uplink data. That is, even though the base station does not receive“RSV”, the base station may determine that the channel is “idle” and mayprepare to receive the uplink data. However, in order to efficientlyreceive the data, if “RSV” is not received, the base station maydetermine that the channel is “busy” (i.e., determine that the channelis occupied/used by other devices), may not expect the uplink data, andmay not prepare to receive the uplink data. Referring to FIG. 39, in thecase of the FBE, the reception is deferred up to a next idle period, andthe reception of “RSV” is again expected. Referring to FIG. 40, in thecase of the LBE, “RSV” may be continuously expected or be expectedduring a predetermined time, or the reception of the uplink data may beexpected.

Referring to FIG. 39, the UE2 expects “RSV” in a given idle period andprepares to receive “RSV”. If the UE2 does not receive “RSV” anddetermines that the channel is “idle”, the UE2 occupies the channel andattempts to transmit the uplink data using the allocated resource. Inaddition, the UE2 blocks the channel to prevent the channeloccupancy/use of other devices until the UE2 transmits the uplink data(UL data Tx2) using the allocated resource. If the UE2 does not receive“RSV” and determines that the channel is “busy”, the UE2 does nottransmit the uplink data (UL data Tx 4) and defers the transmission ofthe uplink data until the next idle period.

Referring to FIG. 40, the UE4 expects to receive “RSV” after receivingthe UL Grant, and prepares to receive “RSV”. As a result, similar to thecase of the FBE of FIG. 39, if the UE4 does not receive “RSV” anddetermines that the channel is “idle”, the UE4 occupies the channel andattempts to transmit the uplink data using the allocated resource. Inthis case, the UE4 blocks the channel to prevent the channeloccupancy/use of other devices until the UE4 transmits the uplink datausing the allocated resource. Meanwhile, if the UE4 does not receive“RSV” and determines that the channel is “busy”, the UE4 does nottransmit the uplink data and defers the transmission of the uplink data,and then again waits during a predetermined time (for example, fromafter two subframes to the reception of next UL grant, or indicated timeperiod) to receive “RSV”. In order for the terminal to more efficientlyexpect/receive “RSV”, the base station may notify an expected timing ofthe transmission of “RSV” to the UE4 at a timing at which the UL Grantis transmitted to the UE3, or may notify the expected timing of thetransmission of “RSV” to the UE4 through the UL Grant.

In addition, the base station and the terminal determine that a framefor the uplink data starts from a transmission/reception timing of“RSV”, generate the virtual frame, and then adjust the transmissiontiming of the uplink data after receiving the UL Grant, thereby makingit possible to transmit and receive the data.

FIG. 41 is a view illustrating a method for allocating resources to aplurality of terminals by a self scheduling in a case in which the CCAis the FBE scheme according to an exemplary embodiment and FIG. 42 is aview illustrating a method for allocating resources to a plurality ofterminals by a self scheduling in a case in which the CCA is the LBEscheme according to an exemplary embodiment.

Referring to FIGS. 41 and 42, in the case in which the UL selfscheduling is applied, the base station performs the CCA to occupy/usethe channel, and transmits the UL Grant, thereby allocating theresources. The terminal attempts to transmit the uplink data using theallocated resources. As described above, the terminal may transmit thedata using the channel occupied by the base station, or the terminalitself may occupy the channel and transmit the data as illustrated inFIGS. 41 and 42. In this case, other terminals (UE2 and UE4) maytransmit the data by using “RSV” (i.e., receiving “RSV” instead of theCCA).

FIGS. 43 and 44 are views illustrating a method for transmitting data bya terminal in a case in which a base station simultaneously occupiesuplink/downlink channels according to an exemplary embodiment.

Referring to FIG. 43, the base station performs the CCA based on theFBE, and referring to FIG. 44, the base station performs the CCA basedon the LBE, and the respective terminals (UE1 to UE4) do not perform theCCA and may transmit the uplink data using “RSV” received from the basestation. In this case, the channel occupied by the base station isoperated by a frame configuration, and the base station occupies thechannel for transmitting the uplink data (of the terminal) at the sametime in a process of occupying the channel for transmitting the downlinkdata. In this case, the terminal may transmit the uplink data to thebase station in the resources allocated through the UL Grant, at thetransmission timing of the uplink data of the virtual frame generatedafter the base station occupies the channel.

FIGS. 45 and 46 are views illustrating a method for transmitting data bya terminal in a case in which a base station simultaneously occupiesuplink/downlink channels according to another exemplary embodiment.

Referring to FIG. 45, the base station performs the CCA based on theFBE, and referring to FIG. 46, the base station performs the CCA basedon the LBE, and the respective terminals (UE1 to UE4) do not perform theCCA and may transmit the uplink data using “RSV” received from the basestation. In this case, the base station may apply a new frameconfiguration in other channels depending on the frame configuration ofthe previous occupied channel, and a newly transmitted “RSV” may includean indication informing that the new frame configuration is applied,unlike information of a previous “RSV”. Alternatively, the terminal mayalso determine the frame configuration to be newly applied based on theprevious frame configuration. Alternatively, the frame configurationinformation may also be included in the PDCCH, instead of being includedin “RSV”, and may be transmitted in the upper layer (RRC levelsignaling), or may also be transmitted using MAC CE or the like.Alternatively, as the frame configuration information, the preset valuemay be used. In addition, in this case, an index (i.e., configuration #)generated by indexing of the frame configuration is transmitted to theterminal in advance, thereby making it possible to transmit and receivethe data between the base station and the terminal by an accuratestandard.

Hereinafter, a structure of the subframe varied depending on atransmission format of data will be described in detail.

In order to transmit the uplink data, some of the uplink data are usedas a demodulated reference signal (DM-RS). However, as described above,the DM-RS needs to be changed in a subframe (hereinafter, referred to as“a partial subframe”) including (1−N_(Symb) ^(UL)) only some symbols(e.g., single carrier-frequency division multiple access (SC-FDMA)symbol) of the subframe.

First, in the case in which the number of symbols of the uplink subframesatisfies the following Equation 2, the partial subframe does notinclude the DM-RS.

$\begin{matrix}{N_{symb}^{{partial}\mspace{14mu}{UL}} < {m\left( {{m = 1},2,{{\ldots\mspace{14mu} N_{symb}^{UL}} - 1}} \right)}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

According to an exemplary embodiment, the DM-RS may be configured in aslot unit. One resource block (RB) used for transmitting the uplink datahas the slot unit, and is configured of a resource element (RE) index(k,l). Here, k is a frequency-domain index, l is a time-domain index,and has the number of N_(Symb) ^(UL) symbols.

FIGS. 47 to 54 are views illustrating the DM-RS within the partialsubframe according to an exemplary embodiment.

In FIGS. 47 to 54, a bolded line indicates the partial subframe, and aportion indicated by an oblique line indicates the DM-RS. A method to bedescribed below may be applied to a case in which the DM-RS isconfigured in the slot unit when the partial subframe has the number ofsymbols less than N_(Symb) ^(UL), or has the number of symbols betweenN_(Symb) ^(UL) and 2×N_(Symb) ^(UL). In the case in which a CP is anormal CP, the number of symbols included in one slot is 7, and a symbolat which the DM-RS is positioned is a fourth (l=3) symbol. In the casein which the CP is an extended CP, the number of symbols included in oneslot is 6, and a symbol at which the DM-RS is positioned is a third(l=2) symbol. However, in the case of the partial subframe, since it isnot guaranteed that l is 3 or 2, the DM-RS may be positioned within thepartial subframe according to the following method.

Method 1: a method in which the DM-RS is included in a symbol in whichl=n (n=0, 1, 2, . . . , N_(Symb) ^(UL)−1).

FIGS. 47 and 48 are views illustrating a partial subframe of a method 1according to an exemplary embodiment. In FIGS. 47 and 48, n is 3,N_(Symb) ^(UL) is 7, and N_(Symb) ^(partial UL) of (a) to (g) of FIGS.47 and 48 is sequentially 7, 6, 5, 4, 3, 2, and 1.

Method 2: a method in which the DM-RS is included in a symbol in whichl=└N_(symb) ^(partial UL)/2┘+(N_(Symb) ^(UL)−N_(symb) ^(partial UL)).

FIGS. 49 and 50 are views illustrating a partial subframe of a method 2according to an exemplary embodiment. In FIGS. 49 and 50, N_(Symb) ^(UL)is 7, and N_(Symb) ^(partial UL) of (a) to (g) of FIGS. 49 and 50 issequentially 7, 6, 5, 4, 3, 2, and 1.

Method 3: a method in which the DM-RS is included in a symbol in whichl=┌N_(symb) ^(partial UL)/2┐+(N_(Symb) ^(UL)−N_(symb) ^(partial UL)).

FIGS. 51 and 52 are views illustrating a partial subframe of a method 3according to an exemplary embodiment. In FIGS. 51 and 52, N_(Symb) ^(UL)is 7, and N_(Symb) ^(partial UL) of (a) to (g) of FIGS. 51 and 52 issequentially 7, 6, 5, 4, 3, 2, and 1.

Method 4: a method in which the DM-RS is included in a symbol in whichl=n+(N_(Symb) ^(UL)−N_(symb) ^(partial UL))

-   -   (n=0, 1, 2, . . . , N_(Symb) ^(UL)−1).

FIG. 53 is a view illustrating a partial subframe of a method 4according to an exemplary embodiment. In FIG. 53, n is 3, N_(Symb) ^(UL)is 7, and N_(Symb) ^(partial UL) of (a) to (g) of FIG. 53 issequentially 7, 6, 5, 4, 3, 2, and 1.

Method 5: a method in which the DM-RS is included in a symbol in whichl=(N_(Symb) ^(UL)−N_(symb) ^(partial UL))−n

-   -   (n=0, 1, 2, . . . , N_(Symb) ^(UL)−1).

FIG. 54 is a view illustrating a partial subframe of a method 5according to an exemplary embodiment. In FIG. 54, n is 3, N_(Symb) ^(UL)is 7, and N_(Symb) ^(partial UL) of (a) to (g) of FIG. 53 issequentially 7, 6, 5, 4, 3, 2, and 1.

When the methods 1 to 5 described above are applied, the number ofsymbols included in the partial subframe is less than m (N_(symb)^(partial UL)<m) (here, m=1, 2, . . . , N_(Symb) ^(UL-1)), the DM-RS maynot be included in the partial subframe.

According to another exemplary embodiment, the DM-RS may be configuredin a transmission time interval (TTI) unit (however, in the case inwhich the number of symbols included in the partial subframe is lessthan N_(Symb) ^(UL), the DM-RS may be configured in the slot unit). Inthe case in which the number of symbols included in the partial subframeis N_(Symb) ^(UL)−2×N_(Symb) ^(UL), the DM-RS may be disposed in a totalnumber of symbols (N_(Symb) ^(UL)−2×N_(Symb) ^(UL)) unit (i.e., the TTIunit).

Method 1: a method in which the DM-RS is not disposed in a slot (apartial slot) having the number of symbols less than a normal slot.

FIGS. 55 and 56 are views illustrating a partial subframe of a method 1according to another exemplary embodiment.

Method 2: a method in which the DM-RS is included in a symbol of a fixedposition (e.g., when l=n, n=3) within the slot, in the case in which thepartial subframe includes “slot+partial slot”.

FIGS. 57 and 58 are views illustrating a partial subframe of a method 2according to another exemplary embodiment. In FIGS. 57 and 58, n is 3,N_(Symb) ^(UL) is 7, and N_(Symb) ^(partial UL) of (a) to (g) of FIGS.57 and 58 is sequentially N_(Symb) ^(UL)+7, N_(Symb) ^(UL)+6, N_(Symb)^(UL)+5, N_(Symb) ^(UL)+4, N_(Symb) ^(UL)+3, N_(Symb) ^(UL)+2, andN_(Symb) ^(UL)+1. Referring to FIGS. 57 and 58, the DM-RS is fixedlydisposed at a third symbol in the slot. Therefore, the DM-RS is notdisposed in the left slot of the subframes (e), (f), and (g) of FIG. 57and the right slot of the subframes (e), (f), and (g) of FIG. 58.

Method 3: a method in which the DM-RS is included in a symbol in whichl=└(N_(symb) ^(partial UL)−N_(symb) ^(UL))/2┘.

FIGS. 59 and 60 are views illustrating a partial subframe of a method 3according to another exemplary embodiment. In FIGS. 59 and 60, N_(Symb)^(UL) is 7, and N_(Symb) ^(partial UL) of (a) to (g) of FIGS. 59 and 60is sequentially N_(Symb) ^(UL)+7, N_(Symb) ^(UL)+6, N_(Symb) ^(UL)+5,N_(Symb) ^(UL)+4, N_(Symb) ^(UL)+3, N_(Symb) ^(UL)+2, and N_(symb)^(UL)+1.

Method 4: a method in which the DM-RS is included in a symbol in whichl=┌(N_(symb) ^(partial UL)−N_(symb) ^(UL))/2┐.

FIGS. 61 and 62 are views illustrating a partial subframe of a method 4according to another exemplary embodiment. In FIGS. 61 and 62, N_(Symb)^(UL) is 7, and N_(Symb) ^(partial UL) of (a) to (g) of FIGS. 61 and 62is sequentially N_(Symb) ^(UL)+7, N_(Symb) ^(UL)+6, N_(Symb) ^(UL)+5,N_(Symb) ^(UL)+4, N_(Symb) ^(UL)+3, N_(Symb) ^(UL)+2, and N_(Symb)^(UL)+1.

Method 5: a method in which when the number of DM-RS to be transmittedin the entire TTI is N, the symbols included in the entire TTI aredivided by N, and the DM-RS is included in each N-divided portion byone.

When the uplink data is transmitted through the unlicensed band, thebase station or the terminal efficiently performs the CCA, therebymaking it possible to occupy the resources of the unlicensed band.

FIG. 63 is a block diagram illustrating a wireless communication systemaccording to an exemplary embodiment.

Referring to FIG. 63, a wireless communication system according to anexemplary embodiment includes a base station 6310 and a terminal 6320.

The base station 6310 includes a processor 6311, a memory 6312, and aradio frequency (RF) unit (6313). The memory 6312 may be connected tothe processor 6311 and may store a variety of information for drivingthe processor 6311 or at least one program executed by the processor6311. The RF unit 6313 may be connected to the processor 6311, and maytransmit and receive a wireless signal. The processor 6311 may implementthe functions, the processes, or the methods proposed by the exemplaryembodiments of the present disclosure. Here, a wireless interfaceprotocol layer in a wireless communication system according to anexemplary embodiment of the present disclosure may be implemented by theprocessor 6311. An operation of the base station 6310 according to anexemplary embodiment may be implemented by the processor 6311.

The terminal 6320 includes a processor 6321, a memory 6322, and a RFunit 6323. The memory 6322 may be connected to the processor 6321 andmay store a variety of information for driving the processor 6321 or atleast one program executed by the processor 6321. The RF unit 6323 maybe connected to the processor 6321, and may transmit and receive awireless signal. The processor 6321 may implement the functions, thesteps, or the methods proposed by the exemplary embodiments of thepresent disclosure. Here, a wireless interface protocol layer in awireless communication system according to an exemplary embodiment ofthe present disclosure may be implemented by the processor 6321. Anoperation of the terminal 6320 according to an exemplary embodiment maybe implemented by the processor 6321.

According to the exemplary embodiment of the present disclosure, thememory may be internal or external of the processor, and may beconnected to the processor by various means which are already known. Thememory is a variety of types of volatile or non-volatile storing medium.For example, the memory may include a read-only memory (ROM) or a randomaccess memory (RAM).

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A method for transmitting a physical uplinkshared channel (PUSCH) by a terminal, the method comprising: receivingan uplink resource information from a base station through an unlicensedband; and transmitting the PUSCH by using a partial subframe belongingto an uplink resource of the unlicensed band corresponding to the uplinkresource information, the partial subframe including fewer symbols thana full subframe, wherein the uplink resource information indicates anending symbol of the partial subframe carrying the PUSCH.
 2. The methodof claim 1, further comprising: transmitting a special signal forpreventing other devices from occupying the unlicensed band before thePUSCH is transmitted when the unlicensed band is occupied by theterminal.
 3. The method of claim 1, further comprising: performing aclear channel assessment (CCA) after receiving an uplink grant, whereinthe uplink grant includes the uplink resource information; andtransmitting the PUSCH when the unlicensed band is occupied after theCCA.
 4. The method of claim 3, wherein the performing of the CCAincludes: selecting a symbol for the CCA from among a plurality ofsymbols in a subframe; and performing the CCA at the selected symbol,wherein the selected symbol is located before the partial subframe. 5.The method of claim 1, wherein the ending symbol of the partial subframeis a last symbol of a first slot of the partial subframe.
 6. The methodof claim 1, wherein: the partial subframe includes resources of ademodulation reference signal (DM-RS) used of the PUSCH.
 7. The methodof claim 6, wherein: the partial subframe includes the resources of theDM-RS when the partial subframe has at least predetermined number ofsymbols.
 8. A terminal for transmitting a physical uplink shared channel(PUSCH), the terminal comprising: a processor, a memory, and a radiofrequency (RF) unit, wherein the processor executes a program stored inthe memory to perform: receiving, by using the RF unit, an uplinkresource information from a base station through an unlicensed band; andtransmitting, by using the RF unit, the PUSCH by using a partialsubframe belonging to an uplink resource of the unlicensed bandcorresponding to the uplink resource information, wherein the uplinkresource information indicates an ending symbol of the partial subframecarrying the PUSCH, and the partial subframe including fewer symbolsthan a full subframe.
 9. The terminal of claim 8, wherein the processorexecutes the program to further perform: performing a clear channelassessment (CCA) after receiving an uplink grant, wherein the uplinkgrant includes the uplink resource information; and transmitting, byusing the RF unit, the PUSCH when the unlicensed band is occupied afterthe CCA.
 10. The terminal of claim 9, wherein the processor executes theprogram to further perform: transmitting, by using the RF unit, aspecial signal for preventing other devices from occupying theunlicensed band between the CCA and the transmission of the PUSCH. 11.The terminal of claim 10, wherein when the processor performs theperforming of the CCA, the processor performs: selecting a symbol forthe CCA from among a plurality of symbols in a subframe; and performingthe CCA at the selected symbol, wherein the selected symbol is locatedbefore the partial subframe.
 12. The method of claim 8, wherein theending symbol of the partial subframe is a last symbol of a first slotof the partial subframe.
 13. The method of claim 8, wherein: the partialsubframe includes resources of a demodulation reference signal (DM-RS)used of the PUSCH.
 14. The method of claim 13, wherein: the partialsubframe includes the resources of the DM-RS when the partial subframehas at least predetermined number of symbols.